Array<double, 1, 3> x(8, 25, 3), e(1. / 3., 0.5, 2.);
cout << "[" << x << "]^[" << e << "] = " << x.pow(e) << endl;  // using ArrayBase::pow
cout << "[" << x << "]^[" << e << "] = " << pow(x, e) << endl; // using Eigen::pow
